Frame producing method and frame

ABSTRACT

In this manufacturing method for a frame body, after ring rolling a metal material to form a ring-shaped member, a rectangular member is formed by pressing and deforming this ring-shaped member in the radial direction. At this time, an angle of corner portions that impart the rectangular shape to the rectangular member is formed smaller than an angle of the frame body that is to be obtained by die forging the rectangular member. According to the frame body obtained by this manufacturing method for a frame body, it is possible to increase the mechanical strength, and in particular, the creep strength. Furthermore, when forming the frame body, the occurrence of defects during manufacture may be restrained, it becomes possible to realize a reduction of the amount of waste metal material and the manufacturing time, and thereby this frame body may be formed inexpensively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manufacturing method for a frame bodysuitable for use in the manufacture of specific parts for such asturbine-operated apparatuses and the like.

Priority is claimed on Japanese Patent Application No. 2002-203981, thecontent of which is incorporated herein by reference.

2. Description of Related Art

Conventionally, in gas turbines for electrical generators and the like,a structure is known in which, in order to increase the jet velocity ofthe combustible gas to the turbine blades, a rectangular frame body isprovided on the outlet of the heat chamber through which the combustiongas flows, that is, the open part on the turbine side, and thecross-sectional area of the flow path of the combustion gas is narrowedby this frame body. Generally, the frame body is structured such thatthe thickness in the direction along the open surface of this frame bodydiffers at each of the opposing edges that impart this rectangularshape. Generally, the followings are known as a manufacturing method forthis frame body.

First, among the edges that impart the rectangular shape to the framebody that is to be formed, a square bar is curve molded so as to form arectangular shape. This square bar provides a cross-sectional dimensionthat is equal to the thickest width in the direction along the opensurface of this frame body. At this time, both end surfaces of thesquare bar are abutted, these end surfaces are subsequently joined byflash butt welding, and a rectangular member is formed. In addition,cutting processes are applied to predetermined edges among the edges ofthis rectangular member, and the edges are formed to a predeterminedthickness in the direction along the open surface. Thereby, a frame bodyis formed in which the thickness differs at each of the opposing edgesthat impart the rectangular shape. In addition, methods in which ablanking process and a cutting process are applied to form a frame bodyare generally well-known.

However, according to the conventional manufacturing method for a framebody, first, in the case in which the frame body is formed by using asquare bar, it is necessary that the cross-sectional area of this squarebar be completely uniform in the longitudinal direction, and thus afterthe rectangular member is formed by deforming, cutting processes must beapplied to the edges that are thin. Thus, there is the problem in that alarge amount of waste material is produced. Furthermore, the proportionof the manufacturing time for the frame body occupied by these cuttingprocess time is high and thus the manufacturing time for the frame bodyrequired, and coupled with the problem of the waste, there is theproblem in that the frame bodies become expensive. Next, in the case inwhich blanking processes and cutting processes are applied to a plate toform the frame body, material positioned on the plate at the opening ofthe frame body and the outside of the frame body becomes unnecessary,and thus there is the problem in that very large amount of wastematerial is produced. Furthermore, as described above, there are theproblems that a processing time is protracted and the frame body becomesexpensive.

SUMMARY OF THE INVENTION

In consideration of the problems described above, it is an object of thepresent invention to provide a manufacturing method for a frame body anda frame body that allows a reduction of the amount of waste materialwhen forming the frame body and allows the frame bodies to be formedinexpensively.

In the manufacturing method for a frame body of the present invention,after ring rolling a metal material to form a ring-shaped member, andafter forming a rectangular member by applying pressing in the radialdirection and deforming to the ring-shaped member, the rectangularmember is placed in a mold and pressing and die forging are carried outto form the frame body.

According to the manufacturing method for a frame body of the presentinvention, it becomes possible to form the frame body by restraining toa minimum the number of cutting process steps. Therefore, because itbecomes possible to reduce the amount of waste metal material andshorten the manufacturing time for the frame body, it becomes possibleto manufacture the frame body inexpensively.

In addition, because the frame body is formed from ring-shaped memberthat is formed by ring rolling, it is possible to make the grain flowcontinuous between each of the wall portions that form the frame body.Thereby, the grain flow of the frame body becomes continuous in thecircumferential direction, and thus it becomes possible to realize anincrease in the mechanical strength, in particular, the creep strength,against a force directed from the inside of the frame body towards theoutside.

When forming the rectangular member, the angle of the corner portionsthat impart the rectangular shape to the rectangular member may besmaller than the angle of the frame body after die forging.

In this case, the angle of the corner portion that imparts therectangular shape to the rectangular member may be formed smaller thanthe angle of the frame body, and thus it becomes possible to restrainthe occurrence of underfills at the corner portion of the forged memberwhen die forging the rectangular member. That is, this effect ofrestraining of the occurrence of underfills is particularly remarkablein the following cases.

When die forging the rectangular member, the rectangular member ispressed in the direction that is perpendicular to the direction alongthe open surface thereof, but when the angle of the rectangular memberis large, the inner surface of the corner portion is bitten into by themold, and thereby large burrs occur. As a result, underfills occur inparts of the frame body, that is, the outer surface. However, if theangle of the corner portion of the rectangular member is formed so as tobe smaller, the inside surface of the corner portion is not bitten intoby the mold, and thus it becomes possible to restrain the occurrence ofburrs in the inside surface, and it becomes possible to restrain theoccurrence of underfills.

Furthermore, when the angles of the rectangular member are formed so asto be smaller than those of the frame body to be formed, as a result,these corner portions project outside of this rectangular member, and itbecomes possible to make the length of the circumference in the cornerportion longer. In other words, it is possible to make the volume in thecorner portion large, which means that it is possible to provide pads inthese rectangular members. When die forging is applied to thisrectangular member to form a frame body, it is possible to thicken thewall of the corner portion of this frame body. Therefore, it becomespossible to form corner portions that have thick walls. Therefore, thecorner portions in the frame body at which stress is concentrated arethickened, and thus it is possible to form simply and reliably ahigh-strength frame body.

When forming the rectangular member, an insert may be disposed insidethe ring-shaped member.

In this case, when forming the rectangular member from the ring-shapedmember, the insert is placed inside the ring-shaped member and pressed,and thus it becomes possible to restrain the deformation of therectangular member due to pressing by using the insert. Therefore, itbecome possible to form the rectangular member into the desired shapesimply, and it becomes possible to provide the frame body inexpensively.

When forming the ring-shaped member, the height of the ring-shapedmember in the axial direction may be formed to a height equivalent to aplurality of frame bodies, and using this ring-shaped member, afterforming the rectangular member, this rectangular member may be cut at aheight equivalent to one frame body, and subsequently each of themembers may be die forged.

In this case, when forming the rectangular member, the height is formedto a height equivalent to the plurality of frame bodies to be formed,and subsequently, the rectangular member is cut at a height equivalentto one frame body, and these rectangular members are die forgedseparately to form the frame bodies. Thus, it becomes possible to formthe frame bodies at a high efficiency, and it becomes possible toprovide the frame bodies inexpensively.

The frame body of the present invention is a metal frame body segmentedinto a plurality of wall portions, and the grain flow runs along thelongitudinal direction of the wall portions, and these wall portions arecontinuous with each other.

According to this frame body of the present invention, the grain flowruns along the longitudinal direction of each of the wall portions, andthese wall portions are continuous with each other, that is, the wallportions and the grain flows are continuous in the circumferential.Thus, the mechanical strength, and in particular, the creep strength ofthis frame body is increased against a force directed from the insidetowards the outside.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 through FIG. 5 are explanatory drawings showing the first throughfifth steps of the manufacturing method for the frame body illustratedin an embodiment of the present invention.

FIG. 6 is an enlarged plan view showing the corner of the rectangularmember when the frame body is formed from the rectangular member shownin FIG. 4.

FIG. 7 is an enlarged plan view showing the corner of the rectangularmember when the etching process has been applied to the rectangularmember shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Below, an embodiment of this invention will be explained with referenceto the drawings. FIG. 1 through FIG. 7 are explanatory drawings forexplaining the manufacturing method for the frame body illustrated in anembodiment of this invention.

First, a concavity is formed in the end surface of a metal (for example,a heat resistant metal such as a Ni based alloy) member that has beenbillet processed by heat forging, and then this forged member is formedinto the ring-shaped member 1 shown in FIG. 1 by using a ring rollingmill. The height “A” of the ring-shaped member 1 in the axial directionis determined by taking into account the height in the directionperpendicular to the direction along the open surface of themanufactured frame body, the plastic deformation when pressing in aperpendicular direction during the die forging described below, and thenumber of frame bodies formed from one ring-shaped member 1 and so on.In the present embodiment, the height “A” is set such that it ispossible to manufacture two frame bodies from one ring-shaped member 1.

Here, the schematic structure of forging apparatus 5 that applies acurving process to the ring-shaped member 1 in the next step will bedescribed. As shown in FIG. 2, the forging apparatus 5 has a base 2, afirst punch 3 provided so as to be able to move reciprocally withrespect to the surface of the base 2, and a set of second punches 4provided so as to be able to approach and separate synchronously in adirection that is vertical to the direction of movement of the firstpunch 3. Here, the opposing surfaces of the base 2 and the first punch 3have flat surfaces, and the opposing surfaces of the set of secondpunches 4 are curved surfaces that form convexities in opposingdirections.

A method, in which the ring-shaped member 1 is curve molded by using theforging apparatus 5 formed described above, will be explained. First,the ring-shaped member 1 is installed on the surface of the base 2 thatopposes the first punch 3, and at the same time, the insert 6 isdisposed inside the ring-shaped member 1. Next, the first punch 3 ismoved towards the surface of the base 2, the inner circumferentialsurface of the ring-shaped member 1 is abutted against the surface ofthe insert 6, and at the same time, the ring-shaped member 1 is pressedin the direction of movement of the first punch 3 to attain the desiredthickness, and thereby a curve molded member 8 that provides first wallportions 7 is formed.

Subsequently, as shown in FIG. 3, the first punch 3 is being abuttedagainst the surface of the first wall portions 7 of the curve moldedmember 8, and then, without retracting the first punch 3, the secondpunches 4 are synchronously moved towards each other until the surfaceof the portion of the inner circumferential surfaces of the curve moldedmember 8 on which the first wall portion 7 has not been formed abuts thesurface of the insert 6. At this time, in the curve molded member 8,second wall portions 9 are formed on the surface where the first wallportions 7 have not been formed. Thereby, the first wall portions 7 andthe second wall portions 9 are provided, and at the same time, arectangular member 10 is formed that provides corner portions 13, wherethese corner portions 13 are connected to the first wall portions 7 andthe second wall portions 9.

Here, the thickness of a first wall portion 7 is formed so as to benarrower than the thickness of a second wall portion 9 in the directionof movement of the second punch 4. In addition, due to the curved shapeof the second punches 4, convexities 11 are formed at the middle of thesecond wall portions 9 in the direction of movement of the first punch3, where this convexity 11 is convex towards the inside of therectangular member 10.

Due to the formation of these convexities 11, the angle θ in the cornerportions 13 is smaller than the angle formed in the case in which theconvexities 11 are not formed, that is, in the case in which the surfaceof the second punch 4 that abuts the external circumferential surface ofthe rectangular member 10 is a flat surface. Accompanying this, thecorner portion 13 acquires a shape that projects slightly towards theoutside of the rectangular member 10. Note that in the presentembodiment, the angle θ of the corner portion 13 is formed at an anglethat is smaller than the angle θ1 of the part corresponding to the framebody 12 formed by the die forging described below, and in addition, theamount of the projection of the corner portion 13 is set such that thereis no biting due to the part that forms the outside part of the cornerportion 13 in a metal mold used during the die forging described below.

Subsequently, the rectangular member 10 is removed from the forgingapparatus 5, and at the same time, after the insert 6 that has beendisposed in the rectangular member 10 has been removed, as shown in FIG.4, the rectangular member 10 is cut at a predetermined position L in thedirection perpendicular to the direction along the open surface of therectangular member 10. Thereby, two rectangular members 10 are formedthat have a height that is one half the height “A”.

In addition, after installing this rectangular member 10 in the mold(not illustrated), the frame body 12 has a desired shape shown in FIG.5A is formed by pressing and die forging this rectangular member 10 inthe direction along the height “A”.

Here, the angle θ in the corner portion 13 of the rectangular member 10is formed smaller than the angle θ1 of the corresponding portion 12 c inthe frame body 12. Thereby, when die forging is applied to therectangular member 10, in a metal mold (not illustrated) that movestowards and press-forms this portion 10, the portion that forms theinside of the corner portion 13 of this rectangular member 10 does notbite into the inside of this corner portion 13. Therefore, during thisdie forging, it is possible to restrain the occurrence of burrs in theinside part of the corner portions 13, and it is possible to restrainthe occurrence of underfills in the outside part of the corner portion13.

Furthermore, when the angle θ of the rectangular member 10 is formed soas to be smaller than the angle θ1 of the frame body 12, as a result, asshown in FIG. 6, this corner portion 13 projects towards the outside ofthe rectangular member 10, and thereby it becomes possible to make thecircumference in this corner portion 13 long. In other words, it ispossible to make the volume in the corner portions 13 high, which meansthat it is possible to provide pads in these rectangular members 10.Thus, when die forging is applied to this rectangular member 10 to formthe frame body 12, as shown by the chain lines in FIG. 6, it is possibleto make the wall of the corner portion 12 c of this frame body 12 thick.Therefore, it becomes possible to form the corner portions 12 c, whichare stress concentration locations in the frame body 12, with thickwalls, and thus it is possible to form simply and reliably thehigh-strength frame body 12. Note that because the angle θ of the cornerportion 13 of the rectangular member 10 widens to a desired angle θ1 inthe frame body 12 during this die forging and that the amount ofprojection of the corner portion 13 is set as described above, theoutside of the corner portion 13 is not bitten into by the part thatforms the outside of the corner portion 13 in the metal mold during thedie forging.

The frame body 12 formed as described above is formed by applyingcurving processes and die forging processes to the ring-shaped member 1that has been formed by ring rolling, and thus the frame body 12 isextended in the longitudinal direction of long wall portions 12 a andshort wall portions 12 b that form the frame body 12, and thus the grainflow is continuous between each of the wall portions 12 a and 12 b. Thatis, the grain flow in the circumferential direction of the frame body 12is continuous. Here, the grain flow denotes the state in which thecrystal structure of the metal material is arranged according to thedeformation of this metal material due to the application ofpress-forming, and is also known as a flow line. In addition, it isknown that the mechanical strength is higher in the direction along thisgrain flow than in the direction that is perpendicular thereto.

There are cases in which it is possible to visually confirm the grainflow as streaks on these surfaces by applying an etching process for 10to 15 minutes to the ring-shaped member 1, the rectangular member 10,and the frame body 12, where this etching process uses a mixture of, forexample, hydrochloric acid and hydrogen peroxide. For example, there arecases in which it is possible to visually confirm the grain flow 20 asshown by the chain lines in FIG. 7 in the corner portion 13 when theetching process has been applied to the rectangular member 10.

In addition, as shown in FIG. 5A and FIG. 5B, the frame body 12 can beformed, for example, with the following dimensions: the length “a” ofthe long wall portion 12 a is approximately 500 mm, the length “b” ofthe short wall portion 12 b is approximately 200 mm, the height “c” ofthe frame body 12 is approximately 50 mm, the thickness “d” of the longwall portion 12 a is approximately 25 mm, the thickness “e” of the shortwall portion 12 b is approximately 30 mm, and the distance between thepeak of the outer surface and the peak of the inner surface, that is,the wall thickness “f”, of connection portion between the long wallportion 12 a and the short wall portion 12 b, that is a corner portion12 c of the frame body 12, is approximately 50 mm.

As explained above, according to the manufacturing method for the framebody according to the present embodiment, it is possible to form theframe body 12 by restraining to a minimum the cutting process time.Therefore, it becomes possible to reduce the amount of waste metalmaterial and to shorten the manufacturing time for the frame body 12.Thus, it becomes possible to manufacture the frame body 12 at a lowcost. In addition, when forming the second wall portions 9 and thecorner portions 13, the angle θ of the corner portions 13 can be madesmaller. That is, it becomes possible to form the angle θ of the cornerportions 13 that is smaller than the angle formed when the surface ofthe second punch 4 that abuts the outer surface of the rectangularmember 10 is flat, and furthermore, it is possible to form the angle θof the corner portion 13 so as to be smaller than the desired angle θ inthe frame body 12.

Thereby, when die forging the rectangular member to form the frame body12, the metal mold does not bite into the inner surface of the cornerportions 13, and thus it is possible to restrain the occurrence of burrson the inner surface of the corner portions 13 and to restrain theoccurrence of underfills in the outer surface of the corner portions 13.

In addition, because the insert 6 is disposed inside the ring-shapedmember 1 and pressed when the rectangular member 10 is formed from thering-shaped member 1, it becomes possible to limit the deformation dueto the pressure by using the insert 6. Thus, it becomes possible to formthe rectangular member 10 into the desired shape simply, and it becomespossible to provide the frame body 12 inexpensively.

In addition, taking into consideration the deformation of processingdescribed above, the height “A” of the rectangular member 10 is formedin advance to a height equivalent to a plurality of the frame bodies 12,and after the rectangular member 10 is cut at the cutting positions L,the resulting rectangular members undergo die forging separately to formthe frame bodies 12. Thus, it becomes possible to form the frame bodies12 at a high efficiency, and it becomes possible to provide the framebodies 12 inexpensively.

Furthermore, the frame body 12 is formed by applying curving process anddie forging to the ring-shaped member 1 that has been formed by ringrolling, and thus it is possible to run the grain flow 20 in thelongitudinal direction of each of the wall portions 12 a and 12 b thatform the frame body 12. Thereby, it is possible to make the grain flow20 continuous between each of the wall portions 12 a and 12 b via thecorner portions 12 c. That is, it is possible to make the grain flowcontinuous in the circumferential direction of the frame body 12.Thereby, it is possible to realize an increase in the mechanicalstrength, and in particular, the creep strength, against a force that isdirected from the inside of the frame body 12 towards the outside.

Therefore, in a gas turbine for an electrical generator or the like, aparticularly remarkable effect is attained when this frame body 12 isinstalled on the outlet of the heat chamber through which the combustiongas flows, that is, on the open part of the turbine side, for raisingthe jet velocity of the combustion gas to the turbine blades due totighten the passage of the combustion gas. Specifically, when the framebody 12 is installed as described above, a large force directed from theinside of the frame body 12 towards the outside acts at a hightemperature; therefore, although the creep strength is critical. Becausethe grain flow 20 is continuous in the circumferential direction of theframe body 12, it is possible to realize an increase in the creepstrength of this frame body 12.

In addition, due to repeated starting and stopping of the gas turbinefor an electrical generator, a temperature cycle is applied to the framebody 12, thus and thermal stress is repeatedly applied, thereby, thedurability is critical. However, because the grain flow 20 isestablished as described above, it is possible to realize an improvementin the durability.

In particular, in the manufacturing method for the frame body accordingto the present embodiment, because it becomes possible to form thickcorner portions 12 c, which are locations of stress concentration in theframe body 12, it is possible to realize reliably an improvement in themechanical stress and the durability.

Thereby, it becomes possible to provide a particularly suitable framebody 12 for use in an environment in which a high load is applied at ahigh temperature cycle.

Note that while preferred embodiments of the invention have beendescribed and illustrated above, it should be understood that these areexemplary of the invention and are not to be considered as limiting.Additions, omissions, substitutions, and other modifications can be madewithout departing from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims. For example, the ring-shaped member 1 may be anon-perfect circle. In addition, the rectangular member 10 is notlimited in rectangular shape, and any polygon is suitable. In addition,as shown in FIG. 3 and FIG. 4, the angle θ of the corner portion 13 isnot limited to 90°, and for example, the rectangular member 10 may alsobe of a parallelogram or fan-shape. Furthermore, the height “A” of therectangular member 10 was the height for two units, but the number maybe equal to or greater than this or equal to 1.

The present invention relates to a method of manufacturing a suitableframe body in the manufacturing of a particular part such as a turbinedriven apparatus. In this frame body, it is possible to make the grainflow continuous between each of the wall portions, it is possible toincrease the mechanical strength, and in particular, the creep strength.Furthermore, when forming such a frame body, the occurrence of defectsdue to manufacturing is restrained, and it becomes possible to realize areduction in the amount of waste metal material and the manufacturingtime, and thereby it becomes possible to form the frame bodyinexpensively.

1. A manufacturing method for a frame body that forms a metal framebody, comprising the steps of: ring rolling a metal material to form aring-shaped member; forming a rectangular member by pressing anddeforming the ring-shaped member in radial directions; thereof placingthe rectangular member in a mold, and; pressing and die forging therectangular member.
 2. A manufacturing method for a frame body accordingto claim 1, wherein when the rectangular member is formed, the angle ofa corner portion that imparts the rectangular shape to the rectangularmember is made smaller than the angle in the frame body after dieforging.
 3. A manufacturing method for a frame body according to claim1, wherein when forming the rectangular member, an insert is disposedinside the ring-shaped member.
 4. A manufacturing method for a framebody according to claim 2, wherein when forming the rectangular member,an insert is disposed inside the ring-shaped member.
 5. A manufacturingmethod for a frame body according to claim 1, wherein forming the heightof the ring-shaped member in the axial direction at a height that isequivalent to a plurality of the frame bodies when forming thering-shaped member, cutting the rectangular member at a heightequivalent to the one frame body after forming the rectangular memberusing this ring-shaped member, and die forging these frame bodiesseparately.
 6. A metal frame body comprising wall portions and, whereingrain flows of the wall portions and run in longitudinal directions ofthe wall portions and, respectively, and continue with each other.
 7. Amanufacturing method for a frame body according to claim 2, whereinforming the height of the ring-shaped member in the axial direction at aheight that is equivalent to a plurality of the frame bodies whenforming the ring-shaped member, cutting the rectangular member at aheight equivalent to the one frame body after forming the rectangularmember using this ring-shaped member, and die forging these frame bodiesseparately.
 8. A manufacturing method for a frame body according toclaim 3, wherein forming the height of the ring-shaped member in theaxial direction at a height that is equivalent to a plurality of theframe bodies when forming the ring-shaped member, cutting therectangular member at a height equivalent to the one frame body afterforming the rectangular member using this ring-shaped member, and dieforging these frame bodies separately.
 9. A manufacturing method for aframe body according to claim 4, wherein forming the height of thering-shaped member in the axial direction at a height that is equivalentto a plurality of the frame bodies when forming the ring-shaped member,cutting the rectangular member at a height equivalent to the one framebody after forming the rectangular member using this ring-shaped member,and die forging these frame bodies separately.